In the related art, there is known a drive device for a wagon type vehicle or a one box type vehicle which improves the convenience of a passenger when boarding and disembarking from a vehicle by driving a sliding door, which opens and closes an opening portion provided in a side portion of a vehicle body for boarding and disembarking, via an electric motor.
The sliding door is slidably supported via a roller assembly by a guide rail that extends along a longitudinal direction of the vehicle body. A curved portion is provided in a front portion of the guide rail, which is curved toward a vehicle interior. When the sliding door is driven to a fully closed position, the roller assembly is guided by the curved portion, and the sliding door is drawn toward the inside of the vehicle body such that the sliding door becomes flush with a side surface of the vehicle body.
Meanwhile, the drive device may include a drum around which cables are wound, and an electric motor that rotates the drum in clockwise and counter-clockwise directions. In this type of drive device, the cables wound around the drum are connected to the sliding door via reverse pulleys which are respectively disposed at both front and rear ends of the guide rail. When the electric motor rotates the drum in the clockwise and counter-clockwise directions, either one of a cable routed on the front side of the sliding door or a cable routed on the rear side of the sliding door is wound around the drum, and the other one is unwound from the drum. Accordingly, the sliding door is automatically slid toward an open position or a closed position in such a way that the sliding door is pulled by the cable.
Patent Literature 1 discloses a configuration in which a brushless motor is used as the electric motor of the aforementioned drive device. The electric motor is an inner rotor type motor in which a rotor is provided inside an annular stator. The electric motor is provided with a sensor mechanism that detects the energization time of the electric motor. The sensor mechanism includes a sensor magnet provided on the rotor, and a magnetic field detection element such as a Hall element which is provided on a circuit substrate to detect the magnetic field of the sensor magnet.
This drive device detects the circumferential position of the rotor and controls the energization timing of the electric motor by detecting the magnetic field of the sensor magnet, which is provided on the rotor, via the magnetic field detection element.